A 30mm tube is stronger than a 1" when they weigh the same?
I would think the wall thickness would be a higher value on the smaller diameter tube when the weight is equal. So increasing the diameter and decreasing the wall thickness makes a tube stronger?
And stronger meaning ability to resist flex, or what?
This is a calculator that I found to calculate load factors on tubes with different materials. If you play around with it you'll see that if you go from a 1" tube of aluminum with a 6" span (roughly a scope) it takes almost twice the tubing wall thickness for a 1" tube to equal the same yield strength as a 1.25" tube (closest to 30mm that the table goes). For the yield strengths of the 1" tube to be equal to the 1.25" tube the weight of the 1.25" AL tube is .28 lb/ft vs. .38 lb/ft for the 1" tube. This is assuming the same yield stress for both, which means the pressure level a material can take before it starts to bend and not return to its original shape after the force is removed.
Take a 6" tube of 6061 aluminum that's 1" in diameter with a wall thickness of .120". Compare that to a 6" long 1.25" tube with a wall thickness of .095" which weighs roughly the same (3.04 vs.3.2 ozs.) and the 1.25" tube is 40% stronger.
So in other words, a 30mm aluminum tube of the same
weight will be stronger than a 1" tube even though the 30mm tube will by necessity have a thinner wall thickness to maintain that weight.
Physics is funky sometimes
